1. Field of the Invention
The present invention relates generally to a door lock having a latch bolt which is movable between latching and unlatching positions, a handle for unlatching the bolt, and a key control for selectively permitting and preventing the handle from unlatching the bolt. More particularly, the invention relates to a lock of this type including a key-controlled disconnect linkage for selectively drivingly connecting and disconnecting the handle and the bolt, whereby the handle is, at all times, freely movable between normal and operating positions, but is functional only when the key control is "unlocked" to enable the handle to unlatch the bolt.
While the present invention has particularly advantageous use in conjunction with flush-type door locks used on swinging doors of vehicles, industrial cabinets, electrical equipment enclosures and the like, principles of the invention are not limited in application to such uses.
2. Prior Art
Flush-type door locks including a body, a lock bolt movably carried on the body, and an operating handle for moving the bolt relative to the body are well known. Normally the handle is in a flush or nested position when the bolt is latched. Bolt unlatching is effected by moving the handle to an operating position. Locks of this type are well suited for use on swinging doors of vehicles such as trucks, on merchandise, tool and equipment cabinets, electrical equipment enclosures and the like.
Flush-type, paddle-handle door locks employing key-operated rotatable cams for selectively permitting and preventing unlocking movements of operating handles, and having spring-projected slide bolts, are described in U.S. Pat. Nos. 3,707,862, and 3,668,907 granted Jan. 2, 1973 and June 13, 1972, respectively, to John V. Pastva, Jr. An ornamental appearance employed in locks of this general type is illustrated in U.S. Pat. No. De. 230,132 issued Jan. 29, 1974 to John V. Pastva, Jr.
The provision of a handle disconnect feature in a door lock is desirable in that the presence of such a feature will lessen, if not totally eliminate, incidents of these locks being damaged by would-be intruders. Since the handles of most previously proposed door locks are restrained from moving when the locks are locked, it is common for would-be intruders to attempt to gain entry by applying excessive leverage force to the lock handles. Where handle disconnect features are provided, the lock handles may always be moved freely, but are functional to retract the lock bolts only when the locks are "unlocked." Locks having handle disconnect features can be made practically entryproof short of the application of such forces as will totally destroy the locks.
Door locks employing various types of handle disconnect systems have been proposed. Prior proposals have, however, suffered from a variety of drawbacks including complexities of construction and failures to mount all of the operating parts of a lock on a single body member so that the resulting locks form compact, easy to install units.
3. The Cross-Referenced Disconnect Cases
The present invention and the inventions described in the several referenced Disconnect Cases represent the work products of a continuous and continuing development program which began nearly a decade ago.
The several handle disconnect systems described in the referenced Disconnect Cases were developed by coworkers operating, in some instances independently, and in other instances jointly, as is reflected in the naming of sole and joint inventors. Many of the disconnect system features claimed in separate ones of the referenced Disconnect Cases were developed substantially concurrently.
Where a claim in one of the referenced Disconnect Cases is found to be generic to a development concept utilized in another of these cases, it should be understood that care has been taken to present the generic claim in the case which describes the earliest development of a species that will support the generic claim. In this manner, a careful effort has been made to establish clear lines of demarcation among the claimed subjects matter of this and the several referenced Disconnect Cases. No two of these cases include claims of identical scope.